Endless track and drive transmission therefor



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w. H. PETHICK ENDLESS TRACK AND DRIVE TRANSMISSION THEREFOR Filed Dec. 7, 1944 Oct. 7, 1947.

ms Arr/s- I Oct. 7, 1947.

w. H. PETHICK 2,428,502 ENDLESS TRACK AND DRIVE TRANSMISSION THEREFOR Filed Dec. 7, 1944 2 Sheets-Sheet 2 q; k K

' My Ail/'8' Patented Oct. 7, 1947 OFFICE I ENDLESS TRACK AND DRIVE TRANS- MISSION THEREFOR William H. Pethick, Regina, Saskatchewan,

Canad Application December 7, 1944, Serial No. 567,070

1 Claim.

My invention relates to improvements in the driving means for endless track tractors, and in improvements of the suspension of the chassis thereof, an object of this invention being to pro- Vide a device of the character herewithin described in which the power plant distributes a tractive efiort to four point approximately at the four corners of the unit, the unit or tractor embodying a chassis and a pair of vertically resilient or yieldable supporting assemblies on either side of the chassis each independent of the other so that they may follow the ground contour without transmitting torsion or stress to the chassis, which may therefore be considered in floating suspension between the assemblies aforesaid.

A further object of my invention is to provide a device of the character herewithin described in which the draw-bar is attached in the approximate centre of the unit thereby eliminating any tendency of the front end to rise when exerting a tractive elfort.

A further object of my invention is to provide a device of the character herewithin described which is susceptible to being V-belt driven thereby effecting a considerable saving in weight, metal and cost of machining.

A further object of my invention is to provide a device of the character herewithin described, by which, in view of the four-point distribution of the tractive effort will effect a considerable economy in gasoline consumption.

A further object of my invention is to provide a device of the character herewithin described wherein the crawler track, being carried dynamically at the front and rear ends will give longer service without repair through considerable reduction in the wear of the track pins and bushings.

A further object of my invention is to provide a device of the character herewithin described, in which the power, being distributed by means of V-belts, will provide a certain percentage of slippage between the power plant and the track carriers which will serve to cushion or damp-down sudden shocks, thereby also greatly reducing wear upon the track itself and particularly the pins and bushings thereof, but in addition, reducing wear upon such parts as the engine wristpins.

A further object of my invention is to provide a device of the character herewithin described, which, due to the provision of V-belts between the power plant and the endless track carriers will develop power gradually under heavy load being manufactured and on slippery ground, thereby greatly aiding the tractive efficiency of the unit under such conditions in contrast to the sudden application of tractive efiort when transmitted to gears which takes place in conventional endless track drives, and which so frequently disturbs footing in slippery conditions.

A further object of my invention is to provide a device of the character herewithin described in which the floating chassis should materially reduce the incidence of accidents mainly due to being thrown from the machine, and in addition the onset of dislocations, strains and sprains, but particularly kidney trouble which so often develops in endless track tractor operators after a sustained period of operation of these vehicles.

A further object of my invention is to provide a device of the character herewithin described in which the drive shaft or central axle being so closely adjacent to the ground and in such close proximity to the track idler rollers, provides an ideal gun-carriage when my invention is used as an instrument of war, since the use of jacks and tedious adjusting could be eliminated before firing.

A further object of my invention is to provide a device of the character herewithin described in which the two endless tracks, being able independently to follow the ground contourwill materially increase the possible speed potentialities of a unit fitted with my invention over soft and rough ground.

A further object of my invention is to provide a device of the character herewithin described in which the main drive shaft is susceptible to the well known knee-action type of mounting, which lends itself particularly to the resilient V-belt which I employ. With such a form of mounting for the drive shaft, the high speed potentialities of a unit built according to my invention would be greatly increased.

A further object of my invention is to provide a device of the character herewithin described which could be manufactured at a particularly 0 low cost, the belt-casings, by which I mean the elongated structural members enclosing the belt,

of boiler plate, with the driven pulleys adjacent the track sprockets of skeleton cast iron configuration and the like.

A further object of my invention is to provide a device of the character herewithin described which in addition to being of low manufacturing cost would also be particularly easy and simple to service in contrast to prevailing types of endless track tractor.

semblies 3 each consist -a1lel and elongated structural members 4 and 5,

With the foregoing objects, in view, and such other objects and advantages as will become apparent to those skilled in the art to which this invention relates as this specification proceeds, my invention consists essentially in the arrangement and construction of parts all as hereinafter more particularly described, reference being had to the accompanying drawings, in which:

Figure 1 is a side elevation partly in section illustrating my invention in association with a 1 same showing one of my four-point connections in situ and in plan with the superstructurebroken away, and also illustrating one of my track ,ca r. rying or chassis suppo crawler track removed therefrom.

In the drawings like characters of --referen ce indicate corresponding parts in the different figures. I

In the accompanying drawings-I haveshown a combat tank superstructure-l =a's-being mounted upon the chassis 2, which chassis, it;isfto be -understood, may be of any configurationorsizeaccording to the purpose for which the unit -is -intended when manufactured Extending along the two parallel sides of the 'chas'sisfand' adjacent i thereto are my track carrying chassissupporting-assemblies collectively designated 3."

The track carryingforchassis supporting asof -a 'pair of spaced, parthese members beihgin-theiormof vertically disposed plates of the configuration clearly indicated in Figurefl,and extendingbetween each ofj the two members 'of' each pair at the front and rear ends thereof are stub shafts 6 journalled in the said members andprojecting threbeyond, said shafts supporting, at the other ends thereof andadjacent to theexternal surfaces ofthe members 4 and 5, the track carrying sprocket wheels fl. Also positioned upon the stub shafts G andQcoaxial'with the sprocket' wheels 1 between each pair of plates 4 --and-5 are the'belt driven rollers 8; these members being keyed-to the shafts} for the rotation thereof. 'Th'ese rollers are grooved to receive the V-belts 9, the opposite endsof these belts passing around-a drive roller- I 0 'k'eyed to each of the projecting ends of a -driv'e; shaft H which lies horizontally and parallelitd the axis of rotation of the sprocket wheels 1, between the front and rear pairs thereof the said drive shaft being rotatedby means of afpower plahtjZ positioned approximately centrally of the chassis 2. Around the sprochetwheels extend thetraclgs I 3,: being supportedupon conventional rollers I 4 extending between the plates" 'dand 5, 'and from 5 the foregoing it will be seen-that I'haveprovided means whereby 'tractive effort may be 'applied at the front and rear ends of each'caterpillar track since those belts 9 which extend forwardly to engage the 'front rollersfl will transmit tractive eifortlto the frontsprdckt wheels, while those belts similarly enumerated which xtendrearwardly to the "hind; rollers will transmit tractive efiort to the adj acent rear sprocket Wheels the, same direction. The ehassis2 is supported on the track carrying or chassis s'upportingassemblies which I' have justrdescrib'ed at the four'points l5, the details of the resilient connections between -chassis-and assembly at these points being bestillustrated ting assemblies with the H independently of the 'is connected to thedri ve shait in Figure 2 wherein it will be seen that I provide vertical recesses I6 in the sides of the chassis through the top and bottom ends I! of which extends a rod I8. Projecting inwardly from the opposing surfaces of each of the inner plates 5 is a heavy bracket or lug I9 suitably stiffened by the portions 20, the lug l9 being provided with theaperture 2i so that the rod 18 may extend therethrough.

Upper and lower coilsprings 22 and 23 extend. between the opposite surfaces of the lug and the upper and lower ends of the recess l6 so that normally, it will clearly be recognized that the chassis 2 is directly supported via the springs 22 resting upon the upper surface of the lugs 19.

However, it will also be recognized that by the yieldable .or floating connection or suspension which I have just described, each fthe track carrying or chassis supporting assemblies 3 is free to yield in a vertical plane about the drive shaft chassis and independentlyof the otherassembly as indicated by the dotted lines 24 in Figure 1. Y Finally it is to be noted that myldraw-bar25 l I, as bymean's Iof the-roller bearing mounted "collars 2B1for by any upon each othermechanical expedient, and by :this connection, it is 'apparent that I" achie'vethe object's already set rerun in the'pream'bleto this specification.-

Since various modifications can be madeinmy invention as 'hereinabfove described; and ma y apparently widely diiferent embodiments of same is intended that all matter contained inthe accompan-ying specificationshall be interpreted as illustrativeonly andnot in a limiting sense.

WhatIclai'inasmyinventionisi An endless trackdrive comprising in'combina tion with a chassis; fouriront' and rearpairs-of spaced, track carrying sprocket Wheels, each pair having abelt driven:'whe'e1 'therebetw'een co axial to and secured-' in rotary conne'ction therewith,

said pairsof track carryingsprocketwheels being positioned adjacent eachcorner of said chassis, a drive shaft parallel witl'r'the axis'ofrotationof said pairs of sprocket wheels, said'drive shaft'beingv positioned"between' the front and rear pairs of sprocket wheels, a multi belt drive wheel on 'each' end of saidf shaft-in rotary-alignment with the front and rear tra'ck carryingisprocketwheels Y side of said' chassis, and at least two belts'around each of' saiddrive wheels one ex- -tending forwardly and the' other rearwardly around said 'driven wheelsrespectivelyjto provide a' four point drive for said'track.

WILLIAM HKPETHICK;

'REFEEENCEST- CITED l The following; references "a e of 'recordjin the Pf. 1 .5" P nt P 2,

NITED, TAT S; TEN 

